- Autocatalytic hydrolysis of V-type nerve agents
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Both V-type nerve agents MeP(O)(OR)(SCH2CH2NR′2), VX (R = C2H5; R′ = i-C3H7) and its isomeric analog RVX (the "Russian V-agent", R = i-C4H9; R′ = C2H5), react slowly but completely with an equimolar amount of H2O via exclusive P-S cleavage to produce the corresponding phosphonic acid (MeP(O)(OR)OH) and 2-aminoethanethiol (HSCH2CH2NR′2). The reaction is believed to be initiated by nucleophilic attack of the deprotonated phosphonic acid on the protonated V-agent to produce a diphosphonate intermediate ((MeP(O)(OR))2O) that rapidly hydrolyzes to regenerate the phosphonic acid. The autocatalytic ionic chain reaction is thus continued in the nearly nonaqueous reaction medium. The viscous final product mixture remains reactive toward freshly added trace amounts of the V-agent, giving the same final reaction half-life of 13-15 h at 23 °C. When water is insufficient and depleted, the diphosphonate intermediate accumulates and reacts with the aminoethanethiol to regenerate the V-agent. This autocatalytic hydrolysis process is not observed with a simpler phosphonothioate analog (MeP(O)(OC2H5)(SC2H5)), which suggests that the attack of the phosphonic acid on the V-agent is intramolecularly assisted by the protonated amino group.
- Yang, Yu-Chu,Szafraniec, Linda L.,Beaudry, William T.,Rohrbaugh, Dennis K.,Procell, Lawrence R.,Samuel, John B.
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- Atmospheric chemistry of diethyl methylphosphonate, diethyl ethylphosphonate, and triethyl phosphate
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Rate constants for the reactions of OH radicals and NO3 radicals with diethyl methylphosphonate [DEMP, (C2H5O) 2P(O)CH3], diethyl ethylphosphonate [DEEP, (C 2H5O)2P(O)C2H5], and triethyl phosphate [TEP, (C2H5O)3PO] have been measured at 296 ± 2 K and atmospheric pressure of air using relative rate methods. The rate constants obtained for the OH radical reactions (in units of 10-11 cm3 molecule-1 s-1 were as follows: DEMP, 5.78 ± 0.24; DEEP, 6.45 ± 0.27; and TEP, 5.44 ± 0.20. The rate constants obtained for the NO3 radical reactions (in units of 10-16 cm3 molecule-1 s-1) were the following: DEMP, 3.7 ± 1.1; DEEP, 3.4 ± 1.4; and TEP, 2.4 ± 1.4. For the reactions of O3 with DEMP, DEEP, and TEP, an upper limit to the rate constant of -20 cm3 molecule-1 s-1 was determined for each compound. Products of the reactions of OH radicals with DEMP, DEEP, and TEP were investigated using in situ atmospheric pressure ionization mass spectrometry (API-MS) and, for the TEP reaction, gas chromatography with flame ionization detection (GC-FID) and in situ Fourier transform infrared (FT-IR) spectroscopy. The API-MS analyses show that the reactions are analogous, with formation of one major product from each reaction: C2H5OP(O)(OH)CH3 from DEMP, C 2H5OP(O)(OH)C2H2 from DEEP, and (C2H5O)2P(O)OH from TEP. The FT-IR and GC-FID analyses showed that the major products (and their molar yields) from the TEP reaction are (C2H5O)2P(O)OH (65-82%, initial), CO2 (80 ± 10%), and HCHO (55 ± 5%), together with lesser yields of CH3CHO (11 ± 2%), CO (11 ± 3%), CH3C(O)OONO2 (8%), organic nitrates (7%), and acetates (4%). The probable reaction mechanisms are discussed.
- Aschmann, Sara M.,Tuazon, Ernesto C.,Atkinson, Roger
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- Catalytic degradation of the nerve agent vx by water-swelled polystyrene-supported ammonium fluorides
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The catalytic degradation of the nerve agent VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate) by water-swelled polymer-supported ammonium fluorides is described. VX (0.06-0.53 mol/mol F -) is rapidly degraded (t1/2 ～ 10-30 min) to form the G-analogue (O-ethyl methylphosphonofluoridate), which hydrolyzes (t 1/2 ～ 1-1.5 h) to the nontoxic EMPA (ethyl methylphosphonic acid). The toxic desethyl-VX is not formed. The catalytic effect of fluoride is maintained even when 6 equiv of VX are loaded. GB (O-isopropyl methylphosphonofluoridate) and desethyl-VX agents are also degraded under these conditions.
- Marciano, Daniele,Goldvaser, Michael,Columbus, Ishay,Zafrani, Yossi
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- A Versatile Self-Detoxifying Material Based on Immobilized Polyoxoniobate for Decontamination of Chemical Warfare Agent Simulants
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A decontaminating composite, Mg3Al-LDH-Nb6, has been successfully prepared by immobilizing Lindqvist [H3Nb6O19]5? (Nb6) into a Mg3Al-based layered double hydroxide (Mg3Al-LDH). To our knowledge, this represents the first successful approach to the immobilization of polyoxoniobate. As a versatile catalyst, Mg3Al-LDH-Nb6 can effectively catalyze the degradation of both vesicant and nerve agent simulants by multiple pathways under mild conditions. Specifically, the sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES), is converted into the corresponding nontoxic 2-chloroethyl ethyl sulfoxide (CEESO) by selective oxidation, whereas the Tabun (G-type nerve agent) simulant, diethyl cyanophosphonate (DECP), and the VX (V-type nerve agent) simulant, O,S-diethyl methylphosphonothioate (OSDEMP), are detoxified through hydrolysis and perhydrolysis, respectively. A possible mechanism is proposed on the basis of control experiments and spectroscopic studies. The Mg3Al-LDH-Nb6 composite exhibits remarkable robustness and can be readily reused for up to ten cycles with negligible loss of its catalytic activity. More importantly, a protective “self-detoxifying” material has easily been constructed by integrating Mg3Al-LDH-Nb6 into textiles. In this way, the flexible and permeable properties of textiles have been combined with the catalytic activity of polyoxoniobate to remove 94 % of CEES in 1 h by using nearly stoichiometric dilute H2O2 (3 %) as oxidant with 96 % selectivity.
- Dong, Jing,Lv, Hongjin,Sun, Xiangrong,Wang, Yin,Ni, Yuanman,Zou, Bo,Zhang, Nan,Yin, Anxiang,Chi, Yingnan,Hu, Changwen
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- Effective, Facile, and Selective Hydrolysis of the Chemical Warfare Agent VX Using Zr6-Based Metal-Organic Frameworks
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The nerve agent VX is among the most toxic chemicals known to mankind, and robust solutions are needed to rapidly and selectively deactivate it. Herein, we demonstrate that three Zr6-based metal-organic frameworks (MOFs), namely, UiO-67, UiO-67-NH2, and UiO-67-N(Me)2, are selective and highly active catalysts for the hydrolysis of VX. Utilizing UiO-67, UiO-67-NH2, and UiO-67-N(Me)2 in a pH 10 buffered solution of N-ethylmorpholine, selective hydrolysis of the P-S bond in VX was observed. In addition, UiO-67-N(Me)2 was found to catalyze VX hydrolysis with an initial half-life of 1.8 min. This half-life is nearly 3 orders of magnitude shorter than that of the only other MOF tested to date for hydrolysis of VX and rivals the activity of the best nonenzymatic materials. Hydrolysis utilizing Zr-based MOFs is also selective and facile in the absence of pH 10 buffer (just water) and for the destruction of the toxic byproduct EA-2192.
- Moon, Su-Young,Wagner, George W.,Mondloch, Joseph E.,Peterson, Gregory W.,DeCoste, Jared B.,Hupp, Joseph T.,Farha, Omar K.
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- Enzymatic neutralization of the chemical warfare agent VX: Evolution of phosphotriesterase for phosphorothiolate hydrolysis
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The V-type nerve agents (VX and VR) are among the most toxic substances known. The high toxicity and environmental persistence of VX make the development of novel decontamination methods particularly important. The enzyme phosphotriesterase (PTE) is capable of hydrolyzing VX but with an enzymatic efficiency more than 5 orders of magnitude lower than with its best substrate, paraoxon. PTE has previously proven amenable to directed evolution for the improvement of catalytic activity against selected compounds through the manipulation of active-site residues. Here, a series of sequential two-site mutational libraries encompassing 12 active-site residues of PTE was created. The libraries were screened for catalytic activity against a new VX analogue, DEVX, which contains the same thiolate leaving group of VX coupled to a diethoxyphosphate core rather than the ethoxymethylphosphonate core of VX. The evolved catalytic activity with DEVX was enhanced 26-fold relative to wild-type PTE. Further improvements were facilitated by targeted error-prone PCR mutagenesis of loop-7, and additional PTE variants were identified with up to a 78-fold increase in the rate of DEVX hydrolysis. The best mutant hydrolyzed the racemic nerve agent VX with a value of kcat/Km = 7 × 104 M-1 s-1, a 230-fold improvement relative to wild-type PTE. The highest turnover number achieved by the mutants created for this investigation was 137 s-1, an enhancement of 152-fold relative to wild-type PTE. The stereoselectivity for the hydrolysis of the two enantiomers of VX was relatively low. These engineered mutants of PTE are the best catalysts ever reported for the hydrolysis of nerve agent VX.
- Bigley, Andrew N.,Xu, Chengfu,Henderson, Terry J.,Harvey, Steven P.,Raushel, Frank M.
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- Magnesium Exchanged Zirconium Metal-Organic Frameworks with Improved Detoxification Properties of Nerve Agents
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UiO-66, MOF-808 and NU-1000 metal-organic frameworks exhibit a differentiated reactivity toward [Mg(OMe)2(MeOH)2]4 related to their pore accessibility. Microporous UiO-66 remains unchanged while mesoporous MOF-808 and hierarchical micro/mesoporous NU-1000 materials yield doped systems containing exposed MgZr5O2(OH)6 clusters in the mesoporous cavities. This modification is responsible for a remarkable enhancement of the catalytic activity toward the hydrolytic degradation of P-F and P-S bonds of toxic nerve agents, at room temperature, in unbuffered aqueous solutions.
- Gil-San-Millan, Rodrigo,López-Maya, Elena,Platero-Prats, Ana E.,Torres-Pérez, Virginia,Delgado, Pedro,Augustyniak, Adam W.,Kim, Min Kun,Lee, Hae Wan,Ryu, Sam Gon,Navarro, Jorge A. R.
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- Alkyl methylphosphonic acids, the degradation products of organophosphorous CWA - preparation and direct quantitative GC-FID analysis
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Seven alkyl methylphosphonic acids, products of hydrolytic degradation of organophosphorus chemical warfare agents, were obtained with a high purity (mostly above 98%), with the aim of being applyed as future certified reference materials. Ethyl (EMPA), i
- Polec, Iwona,Kielczewska, Anna,Konopski, Leszek,Oleksa, Grazyna,Krukowska, Hanna Nowacka,Legocki, Jan
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- Degradation of Paraoxon and the Chemical Warfare Agents VX, Tabun, and Soman by the Metal-Organic Frameworks UiO-66-NH2, MOF-808, NU-1000, and PCN-777
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In recent years, Zr-based metal-organic frameworks (MOFs) have been developed that facilitate catalytic degradation of toxic organophosphate agents, such as chemical warfare agents (CWAs). Because of strict regulations, experiments using live agents are not possible for most laboratories and, as a result, simulants are used in the majority of cases. Reports that employ real CWAs are scarce and do not cover the whole spectrum of agents. We here present a comparative study in which UiO-66-NH2, NU-1000, MOF-808, and PCN-777 are evaluated for their effectiveness in the degradation of paraoxon and the chemical warfare agents tabun, VX, and soman, in N-ethylmorpholine buffer (pH 10) as well as in pure water. All MOFs showed excellent ability to degrade the agents under basic conditions. It was further disclosed that tabun is degraded by different mechanisms depending on the conditions. The presence of an amine, either as part of the MOF structure (UiO-66-NH2) or in the agent itself (VX, tabun), is the most important factor governing degradation rates in water. The results show that MOFs have great potential in future protective applications. Although the use of simulants provides valuable information for initial screening and selection of new MOFs, the use of live agents revealed additional mechanisms that should aid the future development of even better catalysts.
- De Koning, Martijn C.,Van Grol, Marco,Breijaert, Troy
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- Analysis of chemical neutralization products of phosphonothiolates by gas chromatography mass spectrometry
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A series of phosphonothiolates, including the highly toxic O-Ethyl-S-(2-diisopropylamino) ethyl methylphosphonothioate (VX), have been subjected to chemical neutralization reaction with metallic sodium. The phosphonothiolates decompose to their respective phosphonic and phosphonothioic acids and this results in the detoxification of VX. GC/MS technique in both EI and CI mode has been applied for reaction monitoring and final identification of the neutralization products formed in this reaction.
- Gupta,Palit,Dubey,Raza
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- Synthesis of alkyl hydrogen alkylphosphonates
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The synthesis of alkyl hydrogen alkylphosphonates 1 was studied. Different synthetic routes were investigated and it was found that alkylphosphonic anhydrides can serve as ideal precursors for the synthesis of those half-acids. It was also shown that isopropyl phosphonic dichloride reacts in a unique fashion to produce alkyl hydrogen isopropylphosphonates in moderate yields.
- Pienaar, Andre,Erasmus, Cornelis M.,Wentzel, Mauritz,Cowley, Eugene H.
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- Synthesis of macroscopic monolithic metal-organic gels for ultra-fast destruction of chemical warfare agents
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The potential threat that has originated from chemical warfare agents (CWAs) has promoted the development of advanced materials to enhance the protection of civilian and military personnel. Zr-based metal-organic frameworks (Zr-MOFs) have recently been demonstrated as excellent catalysts for decomposing CWAs, but challenges of integrating the microcrystalline powders of Zr-MOFs into monoliths still remain. Herein, we report hierarchically porous monolithic UiO-66-X xerogels for the destruction of CWAs. We found that the UiO-66-NH2xerogel with a larger pore size and a higher surface area than the UiO-66-NH2powder possessed better degradability of 2-chloroethyl ethyl sulfide (2-CEES), which is a sulfur mustard simulant. These UiO-66-X xerogels exhibit outstanding performance for decomposing CWAs. The half-lives of vesicant agent sulfur mustard (HD) and nerve agentO-ethylS-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) are as short as 14.4 min and 1.5 min, respectively. This work is, to the best of our knowledge, the first report on macroscopic monolithic UiO-66-X xerogels for ultrafast decomposition of CWAs.
- Li, Heguo,Pan, Hongjie,Tao, Cheng-An,Wang, Lingyun,Yang, Guang,Zhang, Shouxin,Zhou, Chuan
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p. 22125 - 22130
(2021/07/02)
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- Microwave-assisted ionic liquid-catalyzed selective monoesterification of alkylphosphonic acids—an experimental and a theoretical study
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It is well-known that the P-acids including phosphonic acids resist undergoing direct es-terification. However, it was found that a series of alkylphoshonic acids could be involved in mo-noesterification with C2–C4 alcohols under microwave (MW) irradiation in the presence of [bmim][BF4] as an additive. The selectivity amounted to 80–98%, while the isolated yields fell in the range of 61–79%. The method developed is a green method for P-acid esterification. DFT calculations at the M062X/6–311+G (d,p) level of theory (performed considering the solvent effect of the corresponding alcohol) explored the three-step mechanism, and justified a higher enthalpy of activation (160.6–194.1 kJ·mol–1) that may be overcome only by MW irradiation. The major role of the [bmim][BF4] additive is to increase the absorption of MW energy. The specific chemical role of the [BF4] anion of the ionic liquid in an alternative mechanism was also raised by the computations.
- ábrányi-Balogh, Péter,Drahos, László,Harsági, Nikoletta,Henyecz, Réka,Keglevich, Gy?rgy
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- Influence of cyclic and acyclic cucurbiturils on the degradation pathways of the chemical warfare agent VX
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The highly toxic nerve agent VX is a methylphosphonothioate that degrades via three pathways in aqueous solution, namely through the hydrolysis of the P-O or P-S bonds, or the cleavage of the C-S bond at the 2-aminoethyl residue. In the latter case, an aziridinium ion and a phosphonothioate is formed. Here it is shown that acyclic or cyclic cucurbiturils inhibit these reactions in phosphate buffer at physiological pH and thus stabilise the nerve agent. When using unbuffered basic solutions as the reaction medium, however, in which the P-S or P-O bonds are normally hydrolysed preferentially, cucurbiturils turned out to strongly shift VX degradation towards the cleavage of the C-S bond. Cucurbit[7]uril, in particular, has a so pronounced effect under suitable conditions that it almost completely suppresses the formation of products resulting from the other degradation pathways. Investigations involving VX analogues in combination with computational methods suggest that one reason for the reaction control exerted by the cucurbiturils is the preorganisation of VX for aziridinium ion formation. In addition, cucurbit[7]uril also lowers the transition state of the reaction by stabilising the positive charge developing on the way to the product. Cucurbiturils thus have a marked effect on the reactivity of a highly toxic nerve agent, which potentially allows using them for decontamination purposes. This journal is
- Andrae, Beatrice,Bauer, Daniel,Ga?, Patrick,Koller, Marianne,Kubik, Stefan,Worek, Franz
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supporting information
p. 5218 - 5227
(2020/07/23)
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- Oxidative Detoxification of Sulfur-Containing Chemical Warfare Agents by Electrophilic Iodine
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Mild oxidation of sulfur-containing chemical warfare agents was performed in organic medium by electrophilic iodine reagents. Kinetic experiments on sulfur mustard (HD) showed rapid (t1/2 1/2 ～ 90 min). Higher donor number solvents, such as THF, DMF, or DMSO, showed slower rates with both iodine and NIS. The oxidation of the nerve agent O-ethyl-S-2-(N,N-diisopropylaminoethyl)methylphosphonothioate (VX) selectively to the nontoxic ethyl methylphosphonic acid product exhibited fast rates (t1/2 = 6 min) using NIS in DMSO solution. In all other solvents tested with VX, rates were slower (t1/2 ～ 30-70 min). Oxidation experiments under the same conditions with chloroethyl ethyl sulfide (HD simulant) and O,S-diethyl methylphosphonothioate (VX simulant) led to much faster reaction rates. These transformations are believed to proceed through electrophilic iodine attack on the sulfur moiety and display solvent dependency based on the agents' structural and chemical properties.
- Smolkin, Boris,Levi, Noam,Karton-Lifshin, Naama,Yehezkel, Lea,Zafrani, Yossi,Columbus, Ishay
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p. 13949 - 13955
(2018/11/30)
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- Microwave-assisted activation and modulator removal in zirconium MOFs for buffer-free CWA hydrolysis
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A novel, facile and efficient method was developed for the activation of acetic acid modulated zirconium MOFs. The protocol involves briefly heating the material in water using microwave irradiation. MOF-808, DUT-84 and UiO-66 were all activated in this manner to remove the modulator and organic solvent from the framework post synthesis, with retention of MOF integrity post activation. The degree of activation was characterised by the use of TGA and NMR. The catalytic activity of the activated MOFs and their non-activated counterparts was investigated for chemical warfare agent (CWA) hydrolysis. Upon activation, an increase in the rate of hydrolysis was observed in the degradation of CWA simulant dimethyl 4-nitrophenyl phosphate (DMNP). MOF-808 and DUT-84 were also screened as catalysts for the hydrolysis of the V-series agent VM, with remarkable half-lives obtained for MOF-808 in the absence of any buffers. Currently employed MOF activation procedures involve the use of additional organic solvents post synthesis; we believe this method to be ideally efficacious for the organic desolvation of zirconium MOFs and removing modulator additives.
- Kalinovskyy,Cooper,Main,Holder,Blight
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p. 15704 - 15709
(2017/12/02)
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- Detoxification of Chemical Warfare Agents Using a Zr6-Based Metal–Organic Framework/Polymer Mixture
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Owing to their high surface area, periodic distribution of metal sites, and water stability, zirconium-based metal–organic frameworks (Zr6-MOFs) have shown promising activity for the hydrolysis of nerve agents GD and VX, as well as the simulant
- Moon, Su-Young,Proussaloglou, Emmanuel,Peterson, Gregory W.,DeCoste, Jared B.,Hall, Morgan G.,Howarth, Ashlee J.,Hupp, Joseph T.,Farha, Omar K.
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p. 14864 - 14868
(2016/10/11)
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- Pathways for the Reactions Between Neurotoxic Organophosphorus Compounds and Oximes or Hydroxamic Acids
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To obtain mechanistic insight into the recently demonstrated detoxification ability of β-cyclodextrin derivatives containing substituents with oxime or hydroxamic acid residues, analogous glucose derivatives with the same substituents were treated with cyclosarin (GF), tabun (GA), and O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) in (Tris)-HCl buffer (0.1 m, pH 7.40), and the different reaction pathways were studied by31P NMR spectroscopy and mass spectrometry. Consistent with previous reports, the oxime is phosphonylated by GF, which is followed by elimination of O-cyclohexyl methylphosphonate to afford a nitrile. Reaction of the hydroxamic acid with GA depends on whether the nitrogen atom of the hydroxamic acid bears a substituent or not. The unsubstituted hydroxamic acid affords a stable phosphate ester lacking the cyanide and the dimethylamino group of GA. If the hydroxamic acid is methylated, the initially formed phosphorylated product undergoes a number of transformations, including cleavage of the C–N bond of the hydroxamic acid. Reaction of the hydroxamic acid with VX involves a Lossen rearrangement. These investigations thus show that all investigated nucleophiles are irreversibly modified upon reaction with nerve agents under the chosen conditions, which indicates that cyclodextrins with oximes or hydroxamic acid as substituents are unlikely to afford catalytic nerve-agent scavengers.
- Bierwisch, Anne,Koller, Marianne,Worek, Franz,Kubik, Stefan
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supporting information
p. 5831 - 5838
(2016/12/18)
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- Molecular engineering of organophosphate hydrolysis activity from a weak promiscuous lactonase template
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Rapid evolution of enzymes provides unique molecular insights into the remarkable adaptability of proteins and helps to elucidate the relationship between amino acid sequence, structure, and function. We interrogated the evolution of the phosphotriesteras
- Meier, Monika M.,Rajendran, Chitra,Malisi, Christoph,Fox, Nicholas G.,Xu, Chengfu,Schlee, Sandra,Barondeau, David P.,Hoecker, Birte,Sterner, Reinhard,Raushel, Frank M.
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supporting information
p. 11670 - 11677
(2013/09/02)
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- Role of the P-F bond in fluoride-promoted aqueous VX hydrolysis: An experimental and theoretical study
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Following our ongoing studies on the reactivity of the fluoride ion toward organophosphorus compounds, we established that the extremely toxic and environmentally persistent chemical warfare agent VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate) is exclusively and rapidly degraded to the nontoxic product EMPA (ethyl methylphosphonic acid) even in dilute aqueous solutions of fluoride. The unique role of the P-F bond formation in the reaction mechanism was explored using both experimental and computational mechanistic studies. In most cases, the "G-analogue" (O-ethyl methylphosphonofluoridate, Et-G) was observed as an intermediate. Noteworthy and of practical importance is the fact that the toxic side product desethyl-VX, which is formed in substantial quantities during the slow degradation of VX in unbuffered water, is completely avoided in the presence of fluoride. A computational study on a VX-model, O,S-diethyl methylphosphonothioate (1), clarifies the distinctive tendency of aqueous fluoride ions to react with such organophosphorus compounds. The facility of the degradation process even in dilute fluoride solutions is due to the increased reactivity of fluoride, which is caused by the significant low activation barrier for the P-F bond formation. In addition, the unique nucleophilicity of fluoride versus hydroxide toward VX, in contrast to their relative basicity, is discussed. Although the reaction outcomes were similar, much slower reaction rates were observed experimentally for the VX-model (1) in comparison to VX.
- Marciano, Daniele,Columbus, Ishay,Elias, Shlomi,Goldvaser, Michael,Shoshanim, Ofir,Ashkenazi, Nissan,Zafrani, Yossi
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supporting information
p. 10042 - 10049
(2013/01/15)
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- Detoxification of O, S-diethyl methyl phosphonothiolate (OSDEMP), a simulant of VX, by N, N-dichlorourethane as an effective decontaminating agent
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N, N-Dichlorourethane has been synthesized and characterized by FT-IR, NMR. Efficiency of this compound as decontaminant has been evaluated by the reaction of O, S-diethyl methyl phosphonothiolate (OSDEMP), a simulant of VX at RT. The decontamination reaction has been monitored by gas chromatography (GC) and the products have been identified by GC-MS.
- Singh, Ravindra,Gutch,Acharya,Prabha
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experimental part
p. 1504 - 1509
(2011/12/02)
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- A study of the kinetics of La3+-promoted methanolysis of S-aryl methylphosphonothioates: Possible methodology for decontamination of EA 2192, the toxic byproduct of VX hydrolysis
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The kinetics of the La3+-catalyzed methanolysis of a series of S-aryl methylphosphonothioates (4a-e, phenyl substituents = 3,5-dichloro, 4-chloro, 4-fluoro, 4-H, 4-methoxy) were studied at 25 °C with ss pH control. The reaction involves saturation binding of the anionic substrates to dimeric La3+/methoxide catalysts formulated as La2 3+(-OCH3)x, where x = 2-5 depending on the solution ss pH. Cleavage of the La3+-bound methylphosphonothioates is fast, ranging from 5 × 10-3 s -1 to 5.5 × 10-5 s-1 for substrates 4a-e at a ss pH of 8.4 and 1.6 × 10-1 s-1 to 4 × 10-3s-1 at a ss pH of 11.7. The rate accelerations for the methanolysis of substrates 4a-e, relative to their background methoxide-promoted reactions, average 7 × 1010 and 1.5 × 109, respectively, at sspH's of 8.4 and 11.7. The catalytic system is predicted to cleave EA 2192 (S-2(N,N-di-iso-propylaminoethyl) methylphosphonothioate), a toxic byproduct of the hydrolysis of VX, with a t1/2 between 4 and 8 min at a ss pH of 8.4, and 27 min at a ss pH of 11.7.
- Dhar, Basab B.,Edwards, David R.,Brown, R. Stan
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scheme or table
p. 3071 - 3077
(2011/05/09)
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- Visible-light C-heteroatom bond cleavage and detoxification of chemical warfare agents using titania-supported gold nanoparticles as photocatalyst
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Gold nanoparticles supported on TiO2 effect the detoxification of soman and VX nerve gases and yperite vesicant agent at room temperature upon visible light illumination.
- Neau, Tefan,Cojocaru, Bogdan,Parvulescu, Vasile I.,Omoghi, Vasile,Alvaro, Mercedes,Garcia, Hermenegildo
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supporting information; scheme or table
p. 4050 - 4054
(2011/07/29)
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- Facile hydrolysis-based chemical destruction of the warfare agents VX, GB, and HD by alumina-supported fluoride reagents
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(Chemical Equation Presented) A facile solvent-free hydrolysis (chemical destruction) of the warfare agents VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate), GB (O-isopropyl methylphosphonofluoridate or sarin), and HD (2,2′-dichloroethyl sulfide or sulfur mustard) upon reaction with various solid-supported fluoride reagents is described. These solid reagents include different alumina-based powders such as KF/Al2O3, AgF/KF/Al2O3, and KF/Al2O3 enriched by so-called coordinatively unsaturated fluoride ions (termed by us as ECUF-KF/Al2O3). When adsorbed on these sorbents, the nerve agent VX quickly hydrolyzed (t1/2 range between 0.1-6.3 h) to the corresponding nontoxic phosphonic acid EMPA as a major product (>90%) and to the relatively toxic desethyl-VX (1/2 range between 2.2-161 h). The reaction rates and the product distribution were found to be strongly dependent on the nature of the fluoride ions in the KF/Al2O 3 matrix and on its water content. All variations of the alumina-supported fluoride reagents studied caused an immediate hydrolysis of the highly toxic GB (t1/2 31P, 13C, and 19F MAS NMR.
- Gershonov,Columbus,Zafrani
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supporting information; experimental part
p. 329 - 338
(2009/04/10)
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- DCC-Celite hybrid immobilized solid support as a new, highly efficient reagent for the synthesis of O-alkyl hydrogen alkylphosphonates under solvent-free conditions
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An efficient and solvent-free synthesis of O-alkyl hydrogen alkyl phosphonates is described. The methodology involves the condensation of alkyl phosphonic acids using DCC-Celite under solvent-free conditions.
- Gupta,Kumar, Rajesh,Gupta,Tak, Vijay,Dubey
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p. 1656 - 1659
(2008/09/18)
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- Resolution of chiral phosphate, phosphonate, and phosphinate esters by an enantioselective enzyme library
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An array of 16 enantiomeric pairs of chiral phosphate, phosphonate, and phosphinate esters was used to establish the breadth of the stereoselective discrimination inherent within the bacterial phosphotriesterase and 15 mutant enzymes. For each substrate,
- Nowlan, Charity,Li, Yingchun,Hermann, Johannes C.,Evans, Timothy,Carpenter, Joseph,Ghanem, Eman,Shoichet, Brian K.,Raushel, Frank M.
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p. 15892 - 15902
(2007/10/03)
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- Phosphorus-containing compounds and uses thereof
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This invention concerns a new family of phosphorus-containing compounds containing a moiety JQA— in which:A is absent or is —O—, —S— or —NR2—;Q is absent or (if A is —O—, —S— or —NR2—) Q may be —V—, —OV—, —SV—, or —NR2V—, where V is an aliphatic, heteroaliphatic, aryl, or heteroaryl moiety, such that J is linked to the cyclohexyl ring directly, through A or through VA, OVA, SVA or NR2VA; 1 K is O or S;each occurrence of Y is independently —O—, —S—, —NR2—, or a bond linking a R5 moiety to P;each occurrence of R2 and R5 is independently an aliphatic, heteroaliphatic, aryl, or heteroaryl moiety, or H; andeach occurrence of R6 is independently —PK(YR5)(YR5), —SO2(YR5) or —C(O)(YR5); so long as any R2, or R5 moiety linked directly to P is not H;wherein two R2, R5 and/or R6 moieties may be chemically linked to one another to form a ring;each occurrence of G is independently —O—, —S—, —NR2— or (M)X;each occurrence of M is independently a substituted or unsubstituted methylene moiety, and any M-M′ moiety may be saturated or unsaturated;each occurrence of x is independently an integer from 1-6; and the other variables are as defined herein.
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- Preparation, derivatization with trimethylsilyldiazomethane, and GC/MS analysis of a "pool" of alkyl methylphosphonic acids for use as qualitative standards in support of counterterrorism and the chemical weapons convention
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There are hundreds of nerve agents in the class of alkyl methylphosphonofluoridates covered by Schedule 1 of the CWC (Chemical Weapons Convention). Hydrolysis of these sarin-like nerve agents results in an equal number of alkyl methylphosphonic acids. These alkyl methylphosphonic acids are persistent and provide good evidence of specific agent production or use. In order to support the CWC and counterterrorism activities, it is desirable to have ready access to each of these hydrolysis products for use as qualitative standards. A means for simultaneously producing multiple alkyl methylphosphonates from methylphosphonic acid and the corresponding alcohols was developed. Derivatization of these alkyl methylphosphonic acids with trimethylsilyldiazomethane yields the corresponding methyl esters which are suitable for GC/MS analysis.
- Crenshaw, Michael D.,Cummings, David B.
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p. 1009 - 1018
(2007/10/03)
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- Phosphorus-containing compounds and uses thereof
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This invention concerns a new family of phosphorus-containing compounds containing a moiety JQA—in which: A is absent or is —O—, —S— or —NR2—; Q is absent or (if A is —O—, —S— or —NR2—) Q may be —V—, —OV—, —SV—, or —NR2V—, where V is an aliphatic, heteroaliphatic, aryl, or heteroaryl moiety, such that J is linked to the cyclohexyl ring directly, through A or through VA, OVA, SVA or NR2VA; K is O or S; each occurrence of Y is independently —O—, —S—, —NR2—, or a chemical bond linking a R5 moiety to P; and the other variables are as defined herein.
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- Solid-phase synthesis of some alkyl hydrogen methylphosphonates
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Eleven alkyl hydrogen methylphosphonates of structure RO(HO) P(O)Me were made by phosphoramidite chemistry on hydroxymethyl polystyrene resin; R = Me, Et, n-Pr, i-Pr, n-Bu, n-hexyl, n-octyl, cyclohexyl, cycloheptyl, cyclooctyl, and 3,3-dimethylbutan-2-yl
- Barucki, Hubert,Black, Robin M.,Kinnear, Kenneth I.,Holden, Ian,Read, Robert W.,Timperley, Christopher M.
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p. 2279 - 2286
(2007/10/03)
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- Reaction of VX and GD with gaseous ozone
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Attempts at decontaminating nerve agents VX {O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate} and GD (pinacolyl methylphosphonofluoridate) with gaseous ozone are described. VX reacts like a tertiary amine with oxidation occurring at carbons adjacent to the nitrogen. In this manner a variety of novel VX derivatives still possessing intact P-S bonds are generated, and as such, must be considered to retain formidable toxicity. The major product is O-ethyl S-[2-(isopropylamino)ethyl] methylphosphonothioate. No reaction of GD with ozone occurs under the conditions employed.
- Wagner, George W.,Bartram, Philip W.,Brickhouse, Mark D.,Connell, Theresa R.,Creasy, William R.,Henderson, Vikki D.,Hovanec, Joseph W.,Morrissey, Kevin M.,Stuff, John R.,Williams, Barry R.
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p. 1267 - 1272
(2007/10/03)
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- Reactions of phosphonates with organohaloboranes: New route to molecular borophosphonates
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Phosphonates RPO(OR′)2 (R = Me, R′ = Et (1); R = CH2Ph, R′ = Et (2); R = CH double bond CH2, R′ = Et (3); R = CH2-CH double bond CH2, R′ = Me (4); R = CH2N3, R′ = Et (5)) react with CyBCl2 (6; Cy = C6H11) in a 1:1 molar ratio in toluene at -30 °C to form the primary adducts CyBCl2·O double bond PR(OR′)2 (7-11). These products undergo a thermally induced bis-chlorodealkylation with the formation of mixtures of oligomers [-O-PR(O-)-O-BCy(O-)]n (22-26) having isovalent P-O-B groupings. Under electron impact mass spectral conditions, the ions [RPO3BCy]4-Cy, which may be attributed to tetramers [RPO3BCy]4 (22′-26′), are detected. Compounds 22′-26′ presumably possess a central cubic M4O12P4 framework that is analogous to those found in alumino- and gallophosphate materials. NMR monitoring shows that [CyBCl(μ2-O)2PR(OR′)]2 (12-16) are formed as intermediates in these reactions. These unstable dimers 12-16 possess a cyclic core analogous to the single-four-ring (4R) secondary building units (SBUs) found in zeolites and phosphate molecular sieves. Hydrolysis of 12-16 and 22-26 with methanol at 30 °C gave respectively RPO(OH)(OR′) (17-21) and RPO(OH)2 (27-31). NMR monitoring reveals that the cyclic dimer [Me2B(μ2-O)2P(CH2Ph)(OEt)]2 (35a) is the primary adduct in the reaction of PhCH2PO(OEt)2 (2) with Me2BBr (34). Heating or prolonged storage at room temperature leads to a mixture of 35a, cyclic borophosphonate Me2BC(μ2-O)2P(CH2Ph)(OEt) (35b), and the mixed anhydride of benzylphosphonic acid and dimethylborinic acid (35c).
- Mortier, Jacques
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p. 4266 - 4275
(2008/10/08)
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- Destruction of toxic organophosphorus esters by oxidative α nucleophilic reagent
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Despite its self-decomposition, Magnesium MonoPeroxyPhthalate 4 is an excellent reagent to totally detoxify phosphonothiolate 1 and fluoridate 2 in basic aqueous medium.
- Cristau, H. J.,Torreilles, E.,Cassagne, T.,Lion, C.,Desgranges, M.,et al.
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- The micellar hydrolysis of toxic organophosphorus esters, with sodium perborate and phosphonium or ammonium salts
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During investigations of methods for the destruction of wastes containing toxic phosphorus esters as paraoxon 1 it was found that aqueous solutions of sodium perborate and low quantity of phosphonium and ammonium salts have a very good efficiency.The success in the cleavage of the p-nitrophenoxy group, is related to both the action of activated nucleophiles developing alpha-effect, and the micellar catalysis.Key words: micellar catalysis / toxic organophosphorus esters / paraoxon / decontamination / sodium perborate / phosphonium salt / ammonium salt / alpha effect
- Cristau, H. J.,Ginieys, J. F.,Torreilles, E.
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p. 712 - 716
(2007/10/02)
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- ORGANOPHOSPHORO(THIOPEROXIC) ACIDS: DIRECT OBSERVATION AND REACTIVITY
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Peracid oxidation of organophosphorothioic acids yields novel organophosphoro(thioperoxic) acids (PSOH-isomers) and tentatively their POSH-isomers evident by 31P NMR spectroscopy.These acids or their further oxidation products are phosphorylating and sulfurylating agents.
- Segall, Yoffi,Wu, Shao-Yong,Toia, Robert F.,Casida, John E.
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p. 473 - 476
(2007/10/02)
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